To determine the cause of Zowe runtime problems, a basic first step is to run the verify script on USS.
cd ZOWE_ROOT_DIR/scripts
zowe-verify.sh
The ZOWE_ROOT_DIR is the directory where you installed the Zowe runtime files.
You can also run a script to check the pre-requisites, even after Zowe is installed. You will see errors about port conflicts and possibly available disk space if Zowe is already installed and running - this is normal.
cd INSTALL_DIR/install
zowe-check-prereqs.sh
The INSTALL_DIR is the directory where you un-PAXed the Zowe PAX file.
Neither of these scripts changes your system, so you can run them at any time.